9. Subjects with active tuberculosis requiring treatment within the previous 3 years. Subjects with a positive PPD at screening will not be eligible for the study unless they completed treatment for latent TB and have a negative chest x-ray at enrolment. A PPD response that is equal to or greater than 10 mm should be considered a positive test, although more conservative criteria may be applied as determined by the clinical circumstance and investigator according to published guidelines and/or local standards endorsed by the medical society. Quantiferon assay may replace PPD testing and patients are excluded from the study if the test is positive. Quantiferon positive patients who completed treatment for latent tuberculosis according to the local guidelines may be considered for enrolment.